Hashem gave people bechirah. There are good and bad people in the world and people have the choice to do both good and bad. When it came to the holocaust it was bad people following a very bad person. They did have bechirah and they chose to follow a mad man. The choices yiddin made after the fire is something that WE learned a lot from.
My mother raised us not to judge others. She always told us that there were the frumest of the frum who went into the war and came out total non-believers. And there were the friest of the frie that came out of the war totally devoted to Hashem and became very frum.
So when we speak of the bad that happens we either understand that it is something that man has created or Hashem is testing us in some one. When good happens we do need to understand that it is a gift from Hashem, because either it came from man which was created by Hashem or Hashem answered a prayer or sent us a sheliach. Everything we have comes from Hashem but he does not control our choices.